Field of the Invention
The present invention relates to a methacrylic resin composition, a method for producing the same, and a molded article.
Description of the Related Art
Methacrylic resins typified by polymethyl methacrylate (PMMA) have high transparency and as such, have heretofore been used in a wide range of fields such as optical materials, parts for vehicles, building materials, lenses, household goods, office automation equipment, and lighting equipment.
In recent years, the methacrylic resins have been increasingly used, particularly, in lifestyle products other than optical materials such as materials for vehicles, light guide panels, or films for liquid crystal displays, and their shapes are complicated, thin, and long. The conventional methacrylic resin compositions therefore tend to have the difficulty in molding processes.
In response to such a multitude of growing needs, there has been a demand for a methacrylic resin composition that has higher impact resistance and heat resistance, and higher fluidity than those of the conventional methacrylic resin compositions, while maintaining transparency.
A technique of blending an acrylic rubber polymer with a methacrylic resin has heretofore been known in order to improve impact resistance. In this case, however, there is a tendency to improve impact resistance, but to reduce transparency, heat resistance, and fluidity. Thus, balanced physical properties are very difficult to exert.
A technique of further blending a polymer having a relatively low viscosity with a methacrylic resin composition containing a rubber polymer has also been known in order to improve the fluidity of the methacrylic resin composition. In this case, however, the dispersibility of the rubber polymer tends to be deteriorated with increase in the difference in the viscosity between the low viscous polymer to be blended and the rubber polymer.
Furthermore, a technique of blending a rubber-like elastic body with an acrylic resin, to impart impact resistance to an acrylic resin composition without impairing transparency, has heretofore been known (see e.g., Patent Literature 1).
A technique of specifying the ratios of components having a molecular weight of ⅕ or less of a peak molecular weight (Mp) to thereby obtain an acrylic resin composition, which is composed of an acrylic resin and a rubber polymer and is improved in terms of fluidity, impact resistance, and heat resistance, has also been known (see e.g., Patent Literature 2).